Biodiesel is produced from palm oil and methanol; this methanol could be obtained from gasification of the raw palm oil residual. The complete process includes: pre-treatment of the biomass, gasification, cleaning and conditioning of the gas and the final synthesis of methanol. A review of the gasification stage is carried out, a classification of the existent gasification reactors is presented and the characteristics of three types of gasifiers are detailed. Furthermore, a summary of certain chemical and physical requirements of the gas